A fuel cells is comprised of a fuel electrode, an oxidant electrode and an electrolyte interposed between these electrodes, wherein fuel is supplied to the fuel electrode and an oxidizer is supplied to the oxidant electrode, to generate electricity by an electrochemical reaction of the fuel. Hydrogen is generally used as the fuel. In the meantime, a direct fuel cell that directly utilizes inexpensive and easily handlable methanol as the fuel has been enthusiastically developed in recent years.
When hydrogen is used as the fuel, the reaction at the fuel electrode is as shown in the following equation (1).3H2→6H++6e−  (1)
When methanol is used as the fuel, the reaction at the fuel electrode is as shown in the following equation (2).CH3OH+H2O→6H++CO2+6e−  (2)
In all these cases, the reaction at the oxidant electrode is as shown in the following equation (3).3/2O2+6H++6e−→3H2O  (3)
Patent Document 1 discloses a fuel cartridge that supplies fuel to a fuel cell when the fuel cell is used as a power source for a portable electric device.    [Patent Document 1] Japanese Laid-open patent publication No. 2003-92128.